This invention relates to a method for suppressing carbonaceous deposits and reducing the temperature in the free spaces above coal charges in coking chambers by introducing untreated coke oven gas at a naturally occurring cooler temperature from the free space above a coal charge in the most recently charged one of two adjacent coking chambers into the free space above the coal charge in the adjacent one of the coking chambers. More particularly, the present invention relates to such a method wherein a jumper pipe is utilized to control the flow of coke oven gas essentially by establishing an inert atmosphere in the jumper pipe to prevent the flow of coke oven gases between the coking chambers during the time while coke is pushed from either of the chambers and, if desired, during decarburization of a coking chamber.
The conversion of coal into coke is carried out in a battery of coking chambers wherein the distillation process yields a volatile matter generally referred to in the art as coke oven gas that escapes into the free space above the coal charge in each of the coking chambers. The coke oven gas is drawn through an offtake or ascension pipe at one end of each coking chamber for passage through a damper valve into a collecting main that extends along the entire battery of coke oven chambers. In some coke oven battery arrangements, two gas-collecting mains are used; one main extending along the battery of coke ovens at the machine side, and one main extending along the battery of coke ovens at the coking side. The two gas-collecting mains are coupled by separate ascension pipes to each coking chamber. The function of either a single or two gas-collecting mains for a coke oven battery is to not only collect coke oven gas from the ovens but also to maintain at all times an accurately controlled pressure in the ovens during a coking process since the gas pressure during coking has a pronounced affect on the coke and coal chemicals. The temperature in the free space above a coal charge undergoes dynamic changes throughout the use of the coking chamber. During the actual coking process, the highest free space temperature occurs near the end of the coking process at about 1850.degree. F.; however, higher temperatures in this area of the coking chamber occur during the decarburization process which is carried out while the oven chamber is empty by the introduction of air for combustion of carbon deposits that build up in the free space area, particularly on the roof area of the coking chamber. The decarburization process increases the temperature at the chamber roof. After the decarburization process is completed, the coking chamber receives a charge of coal whereby the large amounts of volatile matter usually referred to as coke oven gases undergo decomposition as they pass into the highly-heated environment at the roof of the coking chamber. At the same time, conditions are such that carbon deposits (which often may be thick due to layering of the deposits) begin to form on the chamber walls in the free space above the coal charge which, in turn, brings about the need, at the conclusion of the coking process, for a longer decarburization time and resulting higher roof temperatures.
A Beimann Main involves operational techniques for one of two gas-collecting mains extending along a coke oven battery to suppress carbonaceous deposits and avoid cracking of the coke oven gas in the space above a coal charge. The structure forming a Beimann Main is essentially the same as that required to form a conventional gas-collecting main. However, a Beimann gas-collecting main is employed to withdraw the coke oven gas from newly-charged coking chambers in which a relatively high pressure exists. The withdrawn gases are cooled by water sprays in the gas main and then cooled coke oven gas is passed downwardly through other ascension pipes into the free space above the coal charge in the various other oven chambers wherein the coking process has proceeded to near the end of the coking period. The pressure of the coke oven gas above the coal charge in a coking chamber which is near the end of the coking process is lower than an average gas pressure taken over the entire coking process. In this way, gas pressure in the coking chambers is controlled throughout the entire coke oven battery and a temperature control is provided for the free space above the coal charges in the oven chambers. The principle of a Beimann Main offers many desirable advantages but at the same time the actual use of a Beimann Main suffers from acute disadvantages which the present invention is designed to overcome. A Beimann Main requires a substantial capital investment to provide all of the various ascension pipes, valves, spray nozzles, water supply and cooling water treatment facilities, and a collector main. The ususal gas-collecting main remains a necessity. The problem of continued maintenance of the Beimann Main represents a substantial and continuous operating expense.
In cases where jumper pipes are used on a single collecting main battery, the necessary valves in the ascension pipes to control the flow of gases therein stick or otherwise malfunction due to deposits of tar whereby, for example, cold coke oven gas escapes through the malfunctioning valve into empty coking chambers. The gas usually burns, with an explosion, but combustion occurs at the end of the coking chamber and causes overheating of the door jamb.